Display (unsigned) transaction's pretty print on the terminal before signing

[tjanez]

SUMMARY

To improve UX when signing transactions with our CLI, we should display (unsigned) transaction's pretty print on the terminal before signing.

For example:

You are about to sign the following transaction:
Content:
  Nonce:  7
  Fee:    2000 (gas limit: 1000, gas price: 2)
  Method: staking.Transfer
  Body:
    To:     oasis1qr3jc2yfhszpyy0daha2l9xjlkrxnzas0uaje4t3
    Amount: 170000000000 base units
Other info:
  Genesis document's hash: 9d1b73470796e7e23f301d67047e4d4ede8ad20a37bf35f9d1b73470796e7e23

If the file signer is used, it should also ask for confirmation, unless --assume-yes (or similar) CLI flag is set, e.g.:

Are you sure you want to continue? [y/N]

If the Ledger signer plugin is used, it could display something like:

Please, follow the instructions on your Ledger device's screen...

to instruct the user to confirm and sign the transaction on his Ledger device.

ISSUE TYPE

• Feature Idea

[Yawning]

Please, follow the instructions on your Ledger device's screen...

I would be against adding special cases for specific external plugins to the oasis-core codebase.

[tjanez]

I would be against adding special cases for specific external plugins to the oasis-core codebase.

Sure, I have no strong preferences over that.